Method of securing a fastening element in concrete



C. W. MEYERS Nov. 27, 1951 METHOD OF SECURING A FASTENING ELEMENT INCONCRETE 2 SHEETS-SHEET 1 Filed Feb. 1, 1950 INVENTOR. CorneZ iusWMeyens' Nov. 27, 1951 c. w. MEYERS 2,576,473

METHOD OF SECURING A FASTENING ELEMENT IN CONCRETE Filed FeB. l, 1950 2SHEETS-SHEET 2 12 a /3 /9;!\ E (-1 Fig.8. 7;) //M/ g g E /e /7' M5 MINVENTOR.

Corneli us WM yens Patented Nov. 27, 1951 METHOD OF SECURING A FASTENINGELEMENT IN CONCRETE Cornelius W. Meyers, Portland, Oreg., assignor toPowder-Power Tool Corp., Portland, reg., a corporation of OregonApplication February 1, 1950, Serial No. 141,763

My invention relates generally to an impact tool which utilize theexplosive discharge of gas from a highly combustible material to drive afastening or material piercing element into and through two overlappedsections of metal, or to drive such a projectile-like device into asolid mass of concrete or masonry.

One of the principal objects of my invention is to provide an effectivemethod of embedding a pointed fastening member into a solid mass ofconcrete or masonry without rupturing and dislodging substantialportions of concrete from the surface thereof adjacent the point ofentry.

As a supplementary feature of the foregoing object, a further feature ofmy invention is to provide a dome-shaped disc, through which saidpiercing or fastening member is projected when it is shot into concrete.

A further and more specific object of my invention is to provide animpact tool for use with said thin metallic disc which will support thedisc in place; will locate said too correcty over the point of entry fora piercing or fastening member discharged from said tool; will hold saiddisc tightly in place by the displaced air ahead of the projectile untilit is pierced by said projectile; will direct the discharged gases frombehind said projectile over said disc, to hold it tightly in place toshield said point of entry; and will prevent said high velocity gasesfrom entering small crevices and blowing out chunks of concrete. That isto say, said impact tool is adapted to locate a disc correctly over thepoint of entry so that it will shield said point from the destructiveforce of said high velocity gases, and will use said high velocity ofsaid gases beneficially to produce an area of high pressure immediatelyadjacent the point of en try. Said area of high pressure tends tocounter act the destructive forces generated by the sudden entry of saidprojectile into a solid mass of concrete, and tends to hold said partstogether adjacent said point of entry somewhat in proportion to thedisrupting forces generated by the entry of said member.

A further object of my invention is to provide a projectile to serve assaid piercing or fastening member, which has a head which constitutes apiston while said projectile is traversing the length of the bore of thebarrel of said machine. Said projectile is thus directed into or througha mass of overlying members to be pinned together.

Said projectile also has utility in connection with a device to be usedpurely as a punching or shearing member, rather than a fastening member.In the latter case, it is desirable that said 5 Claims. (Cl. 1-1) punchbe permitted to pass completely through a sheet of material. This wouldbe prevented if the shank of the device were provided with a largeintegral head serving as a piston. To this end, I make said head andsaid shank in separate pieces and bind them together by some adhesive orby a press fit So that when the shank passes through the plate, the headis released and a smooth hole is formed by said punch withoutsubstantial marking or indentation produced by said larger head.

If said connection has shanks which are threaded, such as studs, whichare to be embedded in a mass of concrete with a portion extendingsubstantially from the surface thereof, the removable head may bethreaded to said stud. Said head may be used as a piston to guide itcentrally, that is axially, of the bore of the barrel, and when saidstud is lodged in material, said head either may be used as a depthgauge, to limit the entry of said stud into said material, or may beused as a nut or fastening device, which can thereafter be used tofasten something to the stud. In the latter case, I deem it preferableto provide two noncircular faces or a plurality of non-circular faces ona minor portion of said head so that said faces may be engaged by awrench to apply force thereto in seating said nut-like head upon thethreaded stem.

A further and more specific object of my invention is to provide animpact tool of this character in which the barrel is smooth-bored anduninterrupted, and is spaced a substantial distance from a surface to beentered. This is accomplished by the use of extension pins. Thus thearea surrounding said pins may serve as a passageway through whichexhaust gases may be discharged. Said barrel thus arranged also permitsthe gases to actually impinge against the surface to be entered. In thislatter case, I preferably shoot said projectiles through discs andutilize said continuing blast of exhausting gases to hold said disctightly about the point of entry, as has previously been commented upon.

A further object of my invention is to provide an impact tool which cannot be discharged inadvertently. To this end, I provide a safety devicewhich has an external trigger which must be depressed in order to permitthe parts of said tool t move into operative position. Further detailsof said impact tool concern the manner in which the charge ofcombustible material may be ignited and burned by the detonating actionof a spring-actuated firing pin, which is set so that a projectile willbe discharged from the barrel of said tool when the parts are arrangedin appropriate firing positions and will not discharge said projectileexcept when said parts are thus arranged.

Further and other details of my invention are hereinafter described withreference to the accompanying drawings, in which:

Fig. l is a longitudinal section through an impact tool embodying myinvention, showing the parts as they are arranged before an explosivecharge is ignited and burned;

V Fig. 2 is a side elevation of said tool with portions shown brokenaway to illustrate the relation of the parts a they exist when theprojecile has been discharged, immediately prior to recoil of thedevices;

Fig. 3 is an elevation of a fastening device with removable piston-likehead, which may serve as a threaded nut upon a stud used in concretework, with a second nut shown thereon to serve as a depth gauge to limitthe penetration of said stud into a mass of concrete or masonry;

Fig. 4 is a cross sectional view taken on the lined-4 in Fig. 3 throughthe removable pistonlike head for said projectile, illustrating themanner in which minor portions of said head are flattened so as toprovide gripping surfaces;

Fig. 5 is a fragmentary sectional view taken on the line 55 in Fig. 1through the barrel of the gun, illustrating the manner in which thesafety catch engages the firing pin carrier body to prevent inadvertentdischarge of a cartridge carrying an explosive charge;

Fig. 6 is a side elevation of a piercing member used in connection withmy invention, said piercing member being provided with a detachable headloosely secured to the shank;

Fig. '7 is a more or less diagrammatic illustration, showing the mannerin which said head becomes detached from the shank when the latter isused as a punch to form a hole in a plate or other member;

Fig. 8 is an enlarged fragmentary longitudinal sectional view throughthe carrier body for the firing pin, showing the devices as they arearranged prior to discharge;

Fig. 9 is a view similar to Fig. 8, showing the parts when said firingpin is actuated to ignite the explosive charge, the projectile beingshown on its way axially of the bore of the gun barrel;

Fig. 10 is a fragmentary view showing the end of an impact tool withextension pins bearing upon a concrete mass into which a projectile isto be embedded and with a disc arranged over themuzzle of said barrel;

Fig. 11 is a view similar to Fig. 10, showing the manner in which theair ahead of said projectile is displaced to move the disc against thesurface of the mass of concrete to be pierced, and with the sharp end ofthe projectile approaching the dome-shaped center of said disc which itis to pierce and to flatten; and

Fig. 12 is a similar view showing said projectile fully embedded in saidmass of concrete, having flattened said disc, and shows the manner inwhich the discharged gases continue to act upon the head of saidprojectile and to be forced downwardly and outwardly over said disc,which shields the surface of the mass of concrete adjacent the point ofentry of said projectile.

An impact tool embodying my invention comprises a frame made up of asleeve 5, closed at one end by a disc 2, to which a handle member 3 issecured by screws 4. Said disc is secured to the sleeve by screws 2a.Intermediate the ends of said sleeve is an annular stop collar 5. Afiring pin carrier body 6 is resiliently held against the stop collar bya recoil spring I. Said recoil spring is quite heavy and exerts asubstantial pressure against said carrier body. It is also initiallycompressed or loaded so that substantial pressure is exerted against thecarrier body even when the parts are at rest. A sectional recoil spring8 lies within the recoil spring I and is spaced from the upper face 51)of the firing pin carrier body a substantial distance. Said springs land 8 together form a compound recoil spring, which is cumulative assaid carrier body is moved backward by the reaction of the explosivecharge, tending to drive the projectile from the muzzle of the barrel.

Said carrier body is a cylindrical member, having a diametric slot 342formed therein, as is shown in Fig. 5. In said slot lies a trigger 9,pivotally mounted on a pin H3. Said trigger is in the form of abell-crank and has a protuberant lip 9a, which underlies and engages acontact hammer II when the parts are arranged as is shown in Fig. 1. Acoiled trigger spring 52 lies between the opposed faces of the hammer Ii and the projecting arm of the trigger and tends to hold said partsspaced. Separation is prevented by the engagement of the lip 9a, withthe under surface of said contact hammer when the firing pin mechanismis cocked. Within the trigger spring i2 is a plug E20,, whose functionit is to prevent the recoil of the parts from breaking said triggerspring. That is, when said trigger spring is compressed upon recoil, thespacing of the contact hammer with the trigger is limited by thepresence of said plug. A firing pin I3 is slidably mounted in an axialpassageway M in the carrier body, and when the trigger is cocked, as isshown in Fig. 1, said firing pin is free to move slightly in saidpassageway with the firing extremity l3a in floating engagement with thecap of a cartridge I5.

A barrel i5 is screw-threaded in the end of the carrier body 6 andslidably engages the bore of the annular stop collar 5. The sleeve Ioverlies the greater portion of the length of the barrel, extending to apoint where only clearance is provided when the parts are in firingposition, as is shown in Fig. 2. In the bore !6a of said barrel is aliner IT. The upper portion of said barrel is cut away so that the linermay be recessed therein and may have substantially the same diameterbore as that of said barrel I6. Within said liner, a projectile l8,constituting a fastening or piercing element, is lodged, as is shown inFig. l. Said projectile is has a shank Isa, a piston-like head iSb, anda projecting flange 680. When I speak of the head as being piston-like,I mean that it slidably engages the bore of said liner and the bore iGaof said barrel. Thus it holds the shank in axial alinement with the axisof said bore and causes it to be directed, point first, from said barrelwhen thus axially alined. The projecting flange overlies the top of theliner l1 and is shearable. That is, when the explosive charge in thecartridge is ignited and expands and generates an explosive gas ofpredetermined compression, it will cause said projecting flange to besheared off and will drive the projectile, point first, down the barrel.When I speak of upwardly and downwardly, I am referring to the relationof the parts as they stand when driving into a floor. Above saidprojectile is a breech plug 19 of tubular section. The ends I; of saidbreech plug are counter-bored to receive the rim portion of thecartridge l5. Both ends are counter-bored so that the breech plug isinterchangeable, and thus care does not have to be exer cised to seethat the right end is up to receive said cartridge. The lower end of thebreech plug bears against the upper surface of the projecting flange ofthe projectile, and the adjacent ends of said breech plug and liner,respectively, clamp said flange between them. Thus, when the buringgases from a combustible charge within the cartridge drives theprojectile along the bore of the barrel, said flange is sheared off andis retained between the adjacent ends of the breech plug and the linerin the manner illustrated in Fig. 9, and the projectile utilizes thepiston-like head to maintain it in alinement, as has been described.

Fixed to the interior of the sleeve l is a longitudinally extendingguide key 29, secured to the sleeve by screws 2i. A guideway 22 in thecarrier body 6 engages said key and prevents relative rotation of saidbody in said sleeve. A pivoted safety button 23 is rotatably mountedupon a pin 23a carried by a housing 23d secured to the guide key andprojectin through a slot in said sleeve, and said safety button rocksabout the axis thereof. It is arranged so that it tends to rotateclockwise, as viewed in Fi 1, about said pin under the influence of acoil spring 23b. A pair of latching points 230 formed on the bottom lieat the lateral side of the guide key and overlie and engage the face 6?)of the carrier body 6, as is shown in Figs. 1 and 5. Thus, when thesafety button is in normal position, it prevents the parts from movinginto firing position. To permit it to be fired, the safety button mustbe pressed, rocking it counter-clockwise to lift said latching pointsout of engagement until they have passed beyond the face 51) of thecarrier body.

The muzzle end 16b of the barrel carries a plurality of extension pinsM. I have illustrated two of said pins which aid in centering the impacttool with regard to a point of entry. This permits rocking about a lineextending through said pins, and if it is desirable to have a more firmsupport, three or four of said pins may be provided. I have found itdesirable, however, to have either two or four of said extension pins,because this arrangement permits the use of guide lines, or center punchmarks on guide lines, to locate the impact tool with re gard to thepoint of entry of a projectile. Said extension pins preferably havesharpened points 24a to seat in counter-punch marks useful in connectionwith the original location of the muzzle end of said barrel. Ipreferably make said extension pins of smaller diameter so as tomaintain the spacing of said pins at the muzzle to maximum distance topermit the rapid escape of gases following the discharge of aprojectile. This will be described in greater detail.

I also use said extension pins as guides upon which a metallic disc 25may be supported. That is, holes are provided in said disc so that saidpins may extend therethrough. The holes are sufficiently large indiameter to permit a sliding fit upon said pins, but are not too largein diam- .eter to remove too much of said disc. This is for the reasonthat said disc plays a rather important function when projectiles areused to pierce and to become imbedded in a mass of concrete. Saidmetallic disc has a dome-shaped central portion 25a, whose diameter issubstantially that of the bore so that it cups into the muzzle of thebarrel, as is shown in Fig. 1. When a projectile is discharged, there isa large amount of air entrapped in the bore of the muzzle, as is shownin Fig. 1, which must be swept out by the projectile, because thepiston-like head fills the entire cross-sectional area of the bore. Saidentrapped air in advance of the projectile tends to drive the metallicdisc against the surface 26 of the mass of concrete. All of the actionshereinafter described happen so quickly that it is diflicult to statewhat happens with great particularit-y. Apparently, however, saidmetallic disc strikes said surface 26 slightly ahead of the projectile,but before it may rebound, it is pinned by the pointed end of the shankof the projectile and pierced thereby. As is shown in Fig. 1, the boreof the barrel adjacent the muzzle end I6b thereof flares slightly, andthus when the head reaches the point of flare, it permits gases toescape around the marginal edges. Thus there is formed an annularenvelope of gases about the projectile, which sweep downwardly andoutwardly about said metallic disc 2-5. Said gas velocities, as well asthe muzzle velocity of the projectile, are high, and the pressuresgenerated by said gases and by said projectile are of high order. It isobvious that, as the pointed end of the shank of the projectile enters amass of concrete, it tends to produce displacement and fracture if thecohesion of the concrete is less than the disrupting forces produced byentry of said projectile. The cohesion of the concrete, of course, isless at the surface than at points lying below the surface. Thus, in theabsence of such metallic disc, said cohesive forces are exceeded andfissures and blowouts of sections of concrete result. The pressure ofsaid disc tends to increase the pressure area adjacent the point ofentry and tends to minimize said fracturing.

. Said disc also tends to shield the area adjacent the point of entryagainst the terrific blast of the escaping gases which would tend toenter any slight fissures to blowout any dislodged portions. As a matterof fact, the velocity of said gases is suflicient to overcome thecohesive forces of the concrete, the gases are directed into a fis sure,tending to dislodge any adjacent particles of concrete. I have foundthat, when said annular discs are used, fracture is maintained to aminimum. Even if slight fractures do exist, said disc tends to overliethem and to cover them, and thus said disc surrounding the head of aprojectile tends to constitute a shield over said area. Said disc doesnot merely cover a fractured section of concrete, but actually limitsfracturing at this point to a substantial degree. The domeshaped center25a also provides a factor of substantial importance, in my opinion,because the marginal edges thereof are held tightly about the point ofentry, but spaced substantially therefrom. When the projectile piercessaid dome and flattens it, it exerts substantial pressure over an areaspaced from the point of entry. I preferably make said dome of a spancomparable to the diameter of the head of the projectile, because it isin this area that fractures are initiated and portions are blown out, ifthe gases strike the surface of the mass of concrete being penetrated.

If projectiles are to be used merely for forming a hole, that is topunch a hole through a sheet of material, I preferably provide one ofthe type shown in Figs. 6 and '7. Such projectile 21 has a shank 21a anda piston-like head 21b, having a shearable lateral flange 210 at the endthereof. Said shank and said head are separable and are only joinedtogether sufficiently to prevent inadvertent separation. To minimize thepoint of contact, I preferably reduce the diameter of the end 21d of theshank, as is shown in Fig. 7, and arrange it in a cavity ofcomplementary size in the head. Said end is either press-fitted into itscavity or is bonded therein by an adhesive or membrane. The friction,adhesive, or other bond between said parts is so slight that the shankwill separate from the head quite easily. Thus, when a shank haspenetrated a plate 28, as is shown in Fig. '7, the head will becomeseparated and will not cause a large deformation or indentation as wouldresult if the head and shank were integral. Also, if said parts wereintegral, I find it difiicult to back out such a punch, because theplate is torn and shreaded by the shank passing therethrough and it canbe dislodged only with great difficulty. By permitting separation,however, a sharp edged punch hole will result and little deformation ofthe plate 28.

If I were to embed a stud 29 in concrete or masonry, it is frequentlydesirable that said stud be threaded so that a nut can be securedthereto. Another factor which is frequently met with is that penetrationof said stud should be limited within close bounds, so that apredetermined portion of said stud will stand free of the surface ofsaid mass of concrete or masonry. To accomplish both of said ends, Iprovide a piston-like head 2911 on the threaded shank 29b, and providean auxiliary nut 29c to limit penetration of the pointed end of theshank in concrete or masonry. The head 29a may be flattened slightly, asat 29d, so as to provide gripping faces, if said head is to be used as anut. Preferably, in the latter case, said nut is turned end-for-endafter the stud is embedded, so that the flattened surface will beoutermost and may thus be more easily gripped. As in the use of theother fastening or piercing elements, a lateral shearable flange 29c isprovided for the head 29a, for the purpose previously expressed inconnection with the other type of projectiles defining fastening orpiercing elements.

In loading the impact tool preparatory to use, the barrel i6 is removedfrom the gun by unscrewing it. from the carrier body E. The breech plugIii is removed from the rearward end of the barrel, permitting thesheared flange I30 of a projectile H3 previously driven from the gun tobe expelled. A new projectile is inserted point first into the breech,the flange [8c resting upon the edge of the liner H. The breech plug isthen inserted in back of the projectile and the cartridge l5 arranged inthe end of the plug. The barrel is then treaded into position within thesleeve, and the gun is thus made ready for use.

The metallic disc 25 is now arranged upon the extension pins 24 with thedome-shaped central portion 25a protruding into the muzzle of the barrel15. The points 25a of the extension pins are then arranged symmetricallyabout a point in the concrete into which the projectile is to be driven.In this position the gun is ready for firing, with the exception thatthe safety button is yet unreleased as shown in Fig. 1 of the drawings.By pressing downwardly upon the rearward end of the safety button 23,the forward end thereof is rotated upwardly about the pivot pin 23a,thereby removing the latch points 230 from engagement with the rear face6?) of the carrier body.

In firing the gun, pressure exerted forwardly upon the handle 3sufiiciently to overcome the force of spring 1 causes the barrel I 6 totelescope rearwardly in relation to the forward movement of the sleeveI. As the barrel and the carrier body 5 attached thereto attain arearward position in the sleeve, the trigger 9 slides along the guidekey 25 and engages the rounded cam projection 20a formed on the latter.As the barrel takes a further rearward position the engagement of thetrigger with the cam projection 26a causes the trigger to pivot in acounterclockwise direction as viewed in Figs. 1 and 2, releasing the lip9a from engagement with the contact hammer H. As illustrated in Fig. 2,the tension of trigger spring I2 then causes the hammer to move forwardwith great force, and the extremity We of the firing pin 13 strikes thecartridge l5.

Referring now to Figs. 9 through 12, the gases developed by the ignitionof the cartridge charge causes the projectile iii to be shot forwardlythrough the barrel [8. The high velocity air passing out of the barrelahead of the onrushing projectile is sufiicient to drive the metallicdisc 25 against the concrete surface 2'6 and to hold it thereagainstuntil the projectile is driven through it and is embedded in theconcrete. As the projectile emerges from the barrel, the propellantgases are directed onto the marginal edges of the disc 25 to continue tohold the latter in place, as described hereinbefore.

When the gun has been fired the release of pressure on the handle by theoperator results in the trigger automatically becoming cocked again andready for a, second firing. Thus it will be apparent from Fig. 2 thatwhen the pressure on the handle 3 is released by the operator the forceof the spring l will cause the sleeve i and the carrier body 6 to moverelatively in opposite directions with respect to each other until thecarrier body 6 and the annular collar 5 come into abutment. When thishappens the latch points 230 will again engage the rearward end 6b ofthe carrier body 6. Meanwhile the engagement of the pin Ila with theannular collar 5 will cause the hammer I! and trigger 9 to be movedcloser together until the trigger lip 9a has again engaged the hammerll.

When the gun has become cocked in this manner the barrel is removed anda new projectile and cartridge may be inserted in the barrel aspreviously described.

I claim:

1. The method of embedding a fastening member having an enlarged headinto a solid mass of concrete comprising, providing a device for drivingsaid member by means of an explosive charge, directing said devicetoward the areato be penetrated but spaced a distance therefrom,arranging a shield having a, dome-shaped center between said device andsaid area, and driving said member through the center of said shield andinto said concrete until the enlarged head has flattened saiddome-shaped center and is seated against said shield, said shieldfunctioning to create a high pressure area on said concrete surfaceadjacent the point of entry of said member and to prevent high velocitygases developed from said explosive charge from impinging on theconcrete surface surrounding the area entered by said member andblasting concrete therefrom, whereby a bond between said member and saidconcrete is formed.

2. The method of embedding a fastening memher having an enlarged headinto a solid mass of concrete by means of an explosive chargecomprising, preliminarily arranging a shield havng a dome-shaped centerbetween said fastening member and said concrete, and driving said memberthrough the center of said shield and into said concrete until theenlarged head has flattened said dome-shaped center and is seatedagainst said shield, said shield functioning to prevent high velocitygases developed from said explosive charge from inpinging on theconcrete surface surrounding the area entered by said member andblasting concrete therefrom, whereby a bond between said member and saidconcrete is formed.

3, The method of securing a fastening element with an enlarged head in asolid mass of a fracturable substance such as concrete and the like,which method consists in employing a device having a gun-like barrel fordriving said element part way into the fracturable substance by means ofan explosive charge, providing spaced members secured to and extendingfrom the muzzle end of said barrel, placing a shield between saidfracturable substance and said muzzle end of said barrel, holding saiddevice with said members pressed against the face of said shield withsaid shield covering and surrounding the area over the spot on thefracturable substance to be penetrated by said element, and driving saidelement through said shield and into said fracturable substance, wherebythe high velocity air forced out from said barrel ahead of said drivenelement will force said shield tightly against the face of saidfracturable substance until said element is driven through said shieldand into place in said fracturable substance and whereby said shieldwill function to prevent the high velocity air and other gases producedby the driving of said element from being impinged on the face of saidfracturable substance while said spaced members will provide escapeoutlets between said muzzle end of said barrel and said shield for thevelocity gases.

4. The method of securing a fastening element with an enlarged head in asolid mass of a fracturable substance such as concrete and the like,which method consists in employing a device having a gun-like barrel fordriving said element part way into the fracturable substance by means ofan explosive charge, providing spaced members secured to and extendingfrom the muzzle end of said barrel, placing a shield having holes forsaid spaced members between said fracturable substance and said muzzleend of said barrel on the face of said fracturable 10 a substance, andinserting said members in said holes, holding said device with saidmembers pressed against the face of said fracturable substance with saidshield covering and surrounding the area over the spot on thefracturable substance to be penetrated by said element, and driving saidelement through said shield and into said fracturable substance, wherebythe high velocity air forced out from said barrel ahead of said drivenelement will force said shield tightly against the face of saidfracturable sub-stance until said element is driven through said shieldand into place in said fracturable substance and whereby said shieldwill function to prevent the high velocity air and other gases producedby the driving of said element from being impinged on the face of saidfracturable substance while said spaced members will provide escapeoutlets between said muzzle endof said barrel and said shield for thevelocity gases.

5. The method of securing a fastening element with an enlarged head in asolid mass of concrete, which method comprises, employing a devicehaving a gun-like barrel for driving said element part way into theconcrete by means of an explosive charge, providing spaced memberssecured to and extending from the muzzle end of said barrel, placing ashield having holes for said spaced members over the muzzle end of saidbarrel with said members extending through said holes, holding saiddevice with said members pressed against the face of said concrete, anddriving said element through said shield and into said concrete, wherebythe high velocity air forced out from said barrel ahead of said drivenelement will force said shield tight- 1y against the face of saidconcrete until said element is driven through said shield and into placein said concrete and whereby said shield will function to prevent thehigh velocity air and other gases produced by the driving of saidelement from being impinged on the face of said concrete while saidspaced members will provide escape outlets between said muzzle end ofsaid barrel and said shield for the velocity gases.

CORNELIUS W. MEYERS.

REFERENCES CITED The following references are of record in the ,file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,388,363 Miller Aug. 23, 19211,984,117 Davis Dec. 11, 1934 2,400,878 Dunn May 28, 1946

